Method of amplifying electrical variations.



No. 781,002. Y I v V I PATENTED'JAN. a1, 1905.

' P. G.'HEWITT. METHOD OF AMPLIFYING ELECTRICAL VARIATIONS APPLICATION nLL n my 16, 1902.

UNITED STATES Patented January 31, 1905.

PATENT OFFICE.

PETER COOPER HEWITT, OF NEW YORK, N Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO COOPER HEWITT ELECTRIC COMPANY, A COR- PORATION OF NEW YORK.

METHOD OF AMPLIFYING ELECTRICAL VARIATIONS.

SPECIFICATION forming part of Letters Patent No. 781,002, dated January 31, 1905.

Application filed may 16, 1902. Serial No. 107,605.

To all whom it may concern.-

Be it known that I, PETER CooPER HEWITT, a citizen of the United States, and a residentof New York, in the county of New York and In certain patents granted to me September '17, 1901, notably in the patents numbered 682,695, 682,696, and 682,697, attention is called to the fact that the resistance of an in:

closed vapor or gas carrying current in an electric circuit varies inversely withthe current carried by the vapor. Accordingly if a varying potential be applied to an apparatusof' the general character described in the patents referred to a variation of current will take place in. the inclosed gas or vapor, and this variation of current will affect the entire circuit in which the apparatus is included, and if the circuit is. so arranged that the gas or vapor apparatus shall represent a considerable portion of the total resistance of the circuit the variations of current thus caused in the conducting gas or vapor will cause comparatively large variations in the entire cir- .cuit.

It iscustomary to operate electric circuits for various purposes by causing variations of potential in the circuit, such variations being utilized to influence appropriate receiving apparatus. In the present invention I avail myself of the peculiar features of electrical resistance of a gas or vaporiconductor to vary or magnify the effects produced by potential variations in a circuit.

By virtue of the described characteristics ofgas or vapor conductors it is impossible, for instance, to translate variations of potential in a circuit into variations of currentor quantity, and inasmuch as the conducting gas or vapor responds practicallyinstantaneously to the applied variations of potential currents of any practical rapidity or frequency can be made to undergo the described transformation and produce their effects upon a suitable re,- ceiving apparatus. As the practical result of anincrease of applied potential is'an increased flow of current, the original electrical impulses in the circuit may produce magnified effects as compared with those which the same impulses would produce if applied directly to the receivers. v

The drawing herewith is a diagram of a typical circuit embodying myinvention.

Inthe drawing, 1 is a suitable source of current supplying a circuit 2. Included in the circuit are a transmitting or potential changing apparatus 3 and a receiving apparatus 4. The transmitting apparatus may be a telegraph-relay, a telephone-transmitter, or any other device adapted to vary the potential of the current ,in the circuit 2. The receiving apparatus 4L may be any suitable receiver adapted to respond to variations of current in the line.

reason of being specially adapted to the purposes of this invention without regard to the matter of light. For this purpose the device may be made with a comparatively short gas or vapor path and having such cross-section that with the current normally traversing it the vapor or gas may become but faintlyluminous.

. The resistance of the circuit outside the device 5 ispractically constant except for the slight variations introduced through the instrumentality of the potential-changing apparatus 3? As the resistance of the device 5 varies substantially inversely with the quantity of the current flowing, or, to put it another way, requiresa definite voltage to pass a definite current therethrough, any diminution, for instance, of the potential applied to its terminals by reason of an increase of resistance on the part of the device 3 will result in not only the diminution of flow of current due to the increased resistance of the device 3, but also to an additional diminution due to the change brought about in the device 5 by the decreased current resulting from the decreased potential at the terminals of the device 5. Likewise an increase of potential at the terminals of the device 5 due to a change of resistance in the outside circuit will cause an increase of current-flow therethrough greatly in excess of the change due to the change of resistance in the other portions of the circuit. In other words, the changes of resistance in other portions of the circuit than the device 5 bring about such variations of conditions in the device 5 as to augment the variations of current-flow through the entire circuit. It should be borne in mind, however, that the resistance of the other portions of the circuit than the device 5 serves in a measure as a balancing resistance for the device 5. Otherwise a decrease of resistance in the external circuit might result in a contin uing unchecked decrease of the total resistance of the circuit including the device 5. The device 5 itself, however, has in a measure a self-corrective tendency within certain limits due to internal variations of resistance resulting from changes in its temperature. The temperature of the device 5 must be taken into consideration when measuring the device for ohmic resistance, as its ohmic resistance varies with the temperature which is brought about by variations in the flow of current and also by the surrounding conditions. The method of controlling these is set forth in the patents hereinbefore referred to. The variations in the amount of current through which the device 5 may be made to operate may be made quite wide by constructing it with the required heat-radiating capacity.

It will now be understood that the receiving apparatus 4 will be affected by a com para-' tively large current and will respond with greater certainty and effectiveness than it otherwise would.

The same amplification of the effects of potential changes in the circuit takes place whatever be the degree of potential increase or variation. 1

When the resistance of the element 5 is made a considerable portion of the total re- .sistance of the circuit, the effect of the changes of resistance in the element named will be very marked, especially when the source of supply is great.

By reason of the gaseous condition of the conducting medium employed the gas or vapor apparatus responds instantly to potential changes in the current without essential loss of energy. In this respect it differs from other materials or substances, because in such other materials or substances work has to be done in the process of reducing the resistance, whereby a loss of energy is caused and the time element becomes a considerable factor, while in my apparatus the amount of material so affected is so small that the energy required to produce the result may be practically neglected.

Means for starting the flow of current through the apparatus are set forth in the patents hereinbefore referred to.

I claim as my invention 1. The method of amplifying potential variations caused in an electric circuit, which consists in applying the said variations to a. quickly-responding medium in the circuit, thereby causing a change in currentflow through such medium, and by such change of current-flow producing in such medium a change of specific resistance resulting in a still further change in current-flmv through the circuit.

2. The method of amplifying energy variations caused in an electric circuit of which an inclosed gas or vapor forms part, and of translating the effects of such amplified variations, which consists in affecting the conducting gas or vapor by variations of current, transforming such variations of current into variations of resistance, and applying such currents to a suitable translating device.

3. The method of amplifying energy variations caused in an electric circuit including an inclosed conducting gas or vapor and electrodes therefor, which consists in affecting the conducting gas or vapor by \wn'iations of current, and thereby transforming such variations into corresponding amplified variations of current.

Signed at New York, in the county of New York and State of New York, this 9th day of May, A. D. 1902.

PETER COOPER .lllUVlll'l.

Witnesses:

\V M. H. UAPEL, GEORGE H. STOCKBRIDUIG. 

